Re: 4.9-rc1 boot regression, ambiguous bisect result

[Dan Williams]

On Thu, Oct 20, 2016 at 5:29 AM, Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx> wrote:
> On Wed, 19 Oct, at 09:04:29PM, Dan Williams wrote:
>> Hi,
>>
>> I am currently unable to boot a Yoga 900 with latest mainline, but 4.8 boots.
>>
>> The symptom is a reboot before the video console is available.
>>
>> I bisected to commit 816e76129ed5 "efi: Allow drivers to reserve boot
>> services forever".  However, that commit is known to be broken.  The
>> proposed fix, commit 92dc33501bfb "x86/efi: Round EFI memmap
>> reservations to EFI_PAGE_SIZE", also exhibits the reboot problem.
>>
>> During the bisect some of the stopping points landed on commits that
>> caused the boot process to hang rather than cause a reboot.  The
>> commits that resulted in a hang are marked "git bisect skip" in this
>> log: https://gist.github.com/djbw/1b501daa98192a42ae848f03bb59c30e
>>
>> I'll try treating those hangs as bad bisect results and re-run the
>> full bisect tomorrow.  In the meantime I wonder if the bisect log
>> implicates a better regression candidate?
>
> Could you mail the dmesg output when booting a known working kernel
> with efi=debug ?

Here it is:

https://gist.github.com/djbw/cae05e721b159d5ad7b146d7a93f5fa2